1. Field of the Invention
This invention relates to an apparatus for the treatment of air way obstructions, and more particularly to an apparatus for creating selective cell necrosis in interior sections of selected head and neck structures without damaging vital structures.
2. Description of Related Art
Sleep-apnea syndrome is a medical condition characterized by daytime hypersomnomulence, morning arm aches, intellectual deterioration, cardiac arrhythmias, snoring and thrashing during sleep. It is caused by frequent episodes of apnea during the patient's sleep. The syndrome is classically subdivided into two types. One type, termed "central sleep apnea syndrome", is characterized by repeated loss of respiratory effort. The second type, termed obstructive sleep apnea syndrome, is characterized by repeated apneic episodes during sleep resulting from obstruction of the patient's upper airway or that portion of the patient's respiratory tract which is cephalad to, and does not include, the larynx.
Treatment thus far includes various medical, surgical and physical measures. Medical measures include the use of medications such as protriptyline, medroxyprogesterone, acetazolamide, theophylline, nicotine and other medications in addition to avoidance of central nervous system depressants such as sedatives or alcohol. The medical measures above are sometimes helpful but are rarely completely effective. Further, the medications frequently have undesirable side effects.
Surgical interventions have included uvulopalatopharyngoplasty, tonsillectomy, surgery to correct severe retrognathia and tracheostomy. In one type of surgical intervention a standard LeFort I osteotomy is combined with a sagittal split ramus osteotomy to advance the maxilla, mandible and chin. Such a procedure may be effective but the risk of surgery in these patients can be prohibitive and the procedures are often unacceptable to the patients.
Physical measures have included weight loss, nasopharyngeal airways, nasal CPAP and various tongue retaining devices used nocturnally. These measures may be partially effective but are cumbersome, uncomfortable and patients often will not continue to use these for prolonged periods of time. Weight loss may be effective but is rarely achieved by these patients.
In patients with central sleep apnea syndrome, phrenic nerve or diaphragmatic pacing has been used. Phrenic nerve or diaphragmatic pacing includes the use of electrical stimulation to regulate and control the patient's diaphragm which is innervated bilaterally by the phrenic nerves to assist or support ventilation. This pacing is disclosed in Direct Diaphragm Stimulation by J. Mugica et al. PACE vol. 10 January-February 1987, Part II, Preliminary Test of a Muscular Diaphragm Pacing System on Human Patients by J. Mugica et al. from Neurostimulation: An Overview 1985 pp. 263-279 and Electrical Activation of Respiration by Nochomovitez IEEE Eng. in Medicine and Biology; June, 1993.
However, it was found that many of these patients also have some degree of obstructive sleep apnea which worsens when the inspiratory force is augmented by the pacer. The ventilation induced by the activation of the diaphragm also collapses the upper airway upon inspiration and draws the patient's tongue inferiorly down the throat choking the patient. These patients then require tracheostomies for adequate treatment.
A physiological laryngeal pacemaker as described in Physiological Laryngeal Pacemaker by F. Kaneko et al. from Trans Am Soc Artif Intern Organs 1985 senses volume displaced by the lungs and stimulates the appropriate nerve to open the patient's glottis to treat dyspnea. This apparatus is not effective for treatment of sleep apnea. The apparatus produces a signal proportional in the displaced air volume of the lungs and thereby the signal produced is too late to be used as an indicator for the treatment of sleep apnea. There is often no displaced air volume in sleep apnea due to obstruction.
One measure that is effective in obstructive sleep apnea is tracheostomy. However, this surgical intervention carries considerable morbidity and is aesthetically unacceptable to many patients. Other surgical procedures include a standard Le Fort I osteotomy in combination with a sagittal split ramus osteotomy. This is a major surgical intervention that requires the advancement of the maxilla, mandible and chin.
Generally, there are two types of snoring. They are distinguished, depending on the localization of their origin. The first type of snoring, velar, is produced by the vibration of all of the structures of the soft palate including the velum, the interior and posterior arches of the tonsils and the uvula. Velar snoring results from a vibration of the soft palate created by the inspiratory flow of air, both nasal and oral, which makes the soft palate wave like a flag. The sound intensity of these vibrations is accentuated by the opening of the buccal cavity which acts as a sound box.
The second type, pharyngeal snoring, is a kind of rattle, including even horn whistling. It is caused by the partial obstruction of the oropharyngeal isthmus by the base of the tongue with, now and again, its total exclusion by the tongue base becoming jammed against the posterior wall of the pharynx. This results in a sensation of breathing, apnea, which constitutes the sleep apnea syndrome. These two types of snoring may easily be combined in the same individual.
For some years there have been surgical techniques for correcting apnea. However, maxillary surgery to cure pharyngeal snoring requires major surgery, with the operation lasting several hours, and the uvula-palatopharnygoplasty procedure to correct velar snoring is not without draw backs. This explains the popularity of prosthesis and other preventive devices.
More recently, portions of the soft palate have been removed by laser ablation. If too much tissue is removed, severe consequences result. The degree of laser ablation is difficult to control and multiple treatments are usually required. Further, patients have a high degree of soreness in their throats for many weeks.
U.S. Pat. No. 4,423,812 discloses a loop electrode design characterized by a bare active wire portion suspended between wire supports on an electrode shaft. Tissue striping is effected with a bare wire, and the adjacent portions of the wire supports an electrode shaft that is made insulating to prevent accidental burns to the patient, allowing the physician to use these insulated parts to help position and guide the active wire portion during the surgical procedure. However, this requires that the physician shave off, during multiple visits, successive thin superficial layers of the obstructing tissues to avoid gross resection and its adverse affects.
U.S. Pat. No. 5,046,512 discloses a method for the treatment of snoring and apnea. The method regulates air flow to the user to an extent comparable to the volume of air which flows through the users nasal passages. An associated apparatus provides a device having a body portion sufficiently wide to separate the users teeth. It includes an air passage comparable in area to the area of the user's nasal passages.
The use of oral cavity appliances has been proposed frequently for the treatment of sleep disorders. It has been recognized that movement of the mandible forward relative to the maxilla can eliminate or reduce sleep apnea and snoring symptoms by causing the pharyngeal air passage to remain open. Several intra-oral dental appliances have been developed which the user wears at night to fix the mandible in an anterior protruded position. Such dental appliances essentially consist of acrylic or elastomeric bit blocks, similar to orthodontic retainers or athletic mouth guards, which are custom fitted to a user's upper and lower teeth. The device may be adjusted to vary the degree of anterior protrusion.
U.S. Pat. 4,901,737 discloses an intra-oral appliance while reducing snoring which repositions the mandible in an inferior, open, and anterior, protrusive, position as compared to the normally closed position of the jaw. Once the dentist or physician determines the operative snoring reduction position for a particular patient, an appropriate mold is taken for the maxillary dentition and of the mandibular dentition to form an appliance template. This device includes a pair of V-shaped spacer members formed from dental acrylic which extend between the maxillary and mandibular dentition to form a unitary mouthpiece.
While such dental appliances have proven effective in maintaining the mandible in a protruded position to improve airway patency, they often result in undesirable side effects. One of the most common side effects is aggravation of the tempromandibular joint and related jaw muscles and ligaments, especially in individuals who have a tendency to grind their teeth during sleep. Aggravation of the tempromandibular joint has be associated with a wide variety of physical ailments, including migraine headaches. Accordingly, many individuals suffering from sleep apnea and snoring disorders are not able to tolerate existing anti-snoring dental appliances for long periods of time.
Opening of obstructed nasal airways by reducing the size of the turbinates has been performed using surgical and pharmaceutical treatments. Examples of surgical procedures include anterior and posterior ethmoidectomy, such as those described in "Endoscopic Paranasal Sinus Surgery" by D. Rice and S. Schaefer, Raven Press, 1988); the writings of M. E. Wigand, Messerklinger and Stamberger; and U.S. Pat. No. 5,094,233. For example, as described in U.S. Pat. No. 5,094,233, the Wigand procedure involves the transection of the middle turbinate, beginning with the posterior aspect, visualization of the sphenoid ostium and opening of the posterior ethmoid cells for subsequent surgery. In the sphenoidectomy step, the ostium of the sphenoid is identified and the anterior wall of the sinus removed. Following this step, the posterior ethmoid cells may be entered at their junction with the sphenoid and the fovea ethmoidalis can be identified as an anatomical landmark for further dissection. In anterior ethmoidectomy, the exenteration of the ethmoids is carried anteriorly to the frontal recess. Complications, such as hemorrhage, infection, perforation of the fovea ethmoidalis or lamina papyracea, and scarring or adhesion of the middle turbinate, are reported in connection with these procedures.
One of the problems encountered as a result of these procedures is postoperative adhesion occurring between the turbinates and adjacent nasal areas, such as medial adhesion to the septum and lateral adhesion to the lateral nasal wall in the area of the ethlmoid sinuses. Otherwise successful surgical procedures may have poor results in these cases. Some surgeons have proposed amputation of a portion of the turbinate at the conclusion of surgery to avoid this complication, resulting in protracted morbidity (crust formation and nasal hygiene problems). The turbinate adhesion problem detracts from these endoscopic surgical procedures. Efforts have been made to reduce the complications associated with the surgical treatment of turbinate tissue, for example by the use of a turbinate sheath device. U.S. Pat. No. 5,094,233.
U.S. Pat. No. 3,901,241 teaches a cryosurgical instrument which is said to be useful for shrinking nasal turbinates. U.S. Pat. No. 3,901,241.
Pharmaceuticals have also been developed for reducing the size of the turbinates. However, pharmaceuticals are not always completely efficacious and generally do not provide a permanent reduction in turbinate size. In addition, pharmaceuticals can have adverse side effects.
A need exists for a method and device for clearing obstructed nasal passageways. It is preferred that the method and device be performable with minimal surgical intervention or post operative complications. It is also preferred that the method and device reduce the size of the turbinate structure without involving surgical cutting or the physical removal of tissue. It is also preferred that the method and device provide a reduction in turbinate structure size to increase air flow in the nasal passageway sufficiently impairing blood flow to the optic nerve and/or retina and create a permanent impairment of vision by the ablation.
It would be desirable to provide an ablation apparatus which eliminates the need for dental appliances for the treatment of snoring and sleep apnea disorders. It would also be desirable to provide a treatment device which is not an intra-oral dental appliance, and which can effectively and safely remove selected portions of the soft palate without providing the patient with undesirable side effects. Further, it would be desirable to provide a tissue ablation device which retains the targeted ablation tissue during the ablation process.
It would be desirable to provide an apparatus for the treatment of snoring which reduces the size of the soft palate and/or uvula with a minimal amount of cutting. It would also be desirable to provide an apparatus for the treatment snoring which is configured to position at least a portion of an energy delivery device into an interior of the soft palate and/or uvula to deliver ablation energy to the interior in order to reduce the size of the soft palate and/or uvula.